An architect behind London’s 30 St Mary Axe skyscraper – also known as the Gherkin – has suggested that it’s time to rethink glass buildings.
Writer and architectural historian Tom Dyckhoff spoke to a series of glass experts on the topic of windows and glass facades in the built environment. The BBC Radio interview, entitled Room With A View, included comments from architect Ken Shuttleworth, who worked with Norman Foster on the 180-metre tall Gherkin skyscraper.
As cities become denser and skyscrapers continue to rise in urban areas, glass facades have become increasingly popular, offering inhabitants breathtaking views, absorbing sunlight for office workers and controlling solar gain to efficiently warm or cool a building.
The demand for light and ventilation at heights continues to rise. No longer are windows cut out of stainless steel structures, and people no longer have to exit a skyscraper at ground level to gain a breath of fresh air. Louvers and breathable facades provide ventilation while glass structures offer light and thermal comfort.
However, global warming has reignited the debate on whether glass is really as ideal as it may seem. In some cases, glass facades are causing concerns from energy inefficiency to creating intense glare.
The conversation comes just months after another landmark glass tower in London, 20 Fenchurch Street (also known as the Walkie Talkie skyscraper), was found to be reflecting intensified heat onto nearby buildings and streets. Late last year, it was nicknamed the “Walkie Scorchie” after its concave structure and glass façade was accused of melting cars, sizzling pedestrians and radiating extreme heat on the sidewalk.
Following months of research, the developers of the Walkie Talkie skyscraper (Land Securities) were given a planning permission to install a permanent “brise soleil” sunshade over the glass structure, which will replace a temporary system from last summer. Work is commencing on the sunshade this month, with the skyscraper still scheduled for completion this year.
The world’s first glass skyscraper, Ludwig Miles Van Der Rohe’s 1921 Friedrichstrasse Skyscraper, was recognised for exploring glass in a modernist way in what MOMA called “the dawning of a new culture.”
However, Shuttleworth would rethink his glass Gherkin tower if it were to be built today.
“The Gherkin is a fantastic building and I think it’s the most liked building in the UK at the moment,” he said in his interview with Dyckhoff. “I think if you were designing it today you’d probably make it different…it wouldn’t be the same product all the way around the building.”
The architect said the cladding would likely be different, given the ways in which environmental attitudes have changed.
“And everything I’ve done over the last 40 years has been rethinking that,” he said. “And I think it’s very important to actually grasp all that to meet the new (UK) building regulations to meet zero carbon by 2019… you know, we have to reduce the amount of windows in buildings or the glass industry has to come up with new products.”
Trade association Glass for Europe said the notion that glass is not environmentally sustainable is ‘a preconceived idea.’
Glass for Europe offers a flat glass product – a solar control glass – that is designed to reduce or prevent solar heating of buildings.
“There are two approaches that can be used: the glass is either tinted (coloured) throughout the material (called a “body tint”), or else it has a microscopically thin and transparent coating on one side,” Glass for Europe’s website reads. “In the body tint approach, the colour causes the glass to absorb solar energy, which is then re-radiated back out and away from the building. Coated glasses immediately reflect the heat away.”
“These technologies reduce the solar heating that tends to take place in large buildings, and thus reduce the need for air conditioning. It is therefore an energy-saving technology.”
Last year, the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) developed a form of smart glass which can monitor and adjust heat transfer depending on the application of voltage.
The nano crystal smart glass has the ability to darken and reduce glare from the sun. The technology has been praised as a bold energy efficient solution for glass building facades, particularly if applied to large urban skyscrapers.
“Smart windows are able to dynamically control the amount of heat and light from the sun that enters a building,” said Berkeley Lab scientist and lead author of the research Delia Milliron in a video describing the technology.
“This is useful to improve comfort for building occupants and also to save energy that is used for thermal control and artificial lighting.”
There have also been developments in glass coating technology that help control the thermal comfort of the indoor environment.
However, in a market where the pressure is high to deliver green skyscrapers, other materials deserve consideration. Wooden skyscrapers are becoming a hot topic, with even the US Government backing them. Earlier this year, The White House Rural Council and the United States Department of Agriculture (USDA) announced a climate-driven initiative that would see architects, builders and engineers trained in the benefits of wood as a structural material.
Wooden skyscrapers have also received support and recognition over several years from leading edge firms such as Skidmore, Owings & Merrill, who developed a structural system for tall timber buildings.